A Randomized Phase II Study Comparing Imatinib and the Combination of Imatinib and Pegylated Interferon Alpha-2b in Newly Diagnosed Non-High Risk Chronic Myeloid Leukemia (CML) Patients in Complete Hematological Remission After Imatinib Induction Therapy.

Imatinib mesylate (IM) 400 mg once daily (OD) is the current standard first-line therapy for CML. Several biological and clinical observations suggest that combining IM with interferon alpha (IFNa) may improve the outcome of treatment.

To compare the effects of standard-dose IM to combination of IM and IFNa in newly diagnosed chronic phase CML patients with an intermediate or low Sokal risk score. The primary end point was to compare the major molecular response (MMR) rate after 12 months between the treatment arms (intention-to-treat analysis).

In a Nordic CML Study Group (NMCLSG: Denmark, Finland, Norway and Sweden) and Israel multicenter study we randomized 114 newly diagnosed CML patients in complete hematological remission following 3 months of IM 400 mg OD induction therapy. The study arms were IM (Glivec, Novartis) and the combination of IM and IFNa 2b (PegIntron, Schering-Plough). IM dose was fixed at 400 mg OD. IFNa was started at 30 μg/week but could be escalated to 50 μg/week or reduced down to 15 μg/week depending on tolerability. Molecular response was evaluated by blood RQ-PCR for BCR-ABL1 and was expressed on the international scale (IS).

As of August 17, 2009, 79 patients were evaluable for primary endpoint and 47 of these were in MMR (59%) The rate of complete cytogenetic response (CCgR) was 68/79 (86%). Nineteen patients (17%) were considered as treatment failures (grade 4 nonhematological adverse event, refusal, loss of CCgR, progression to advanced phase, protocol violation or other reason).

A final analysis will be performed when we have complete data on all randomized patients. The comparison by treatment arm on molecular and cytogenetic responses as well as other relevant data (treatment failures, patients off-treatment for protocol violations, refusal or toxicity) will be presented on site.

Supported by European LeukemiaNet, WP 4.

Simonsson:Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding. BjÖreman:BMS: Consultancy, Honoraria. Mustjoki:BMS: Honoraria. StrÖmberg:Novartis: Honoraria; BMS: Honoraria. Weiss Bjerrum:Novartis: Consultancy, Honoraria; BMS: Consultancy, Honoraria. Gruber:Novartis: Research Funding. Nagler:Novartis: Consultancy. Porkka:Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding.